JEB is pleased to present the first special issue we have published, Sex uncovered: the evolutionary biology of reproductive systems. The evolution of mating systems and the distribution of sexual versus asexual reproduction is a classical question in evolutionary biology, and this issue brings together reviews and empirical studies to give an excellent overview of our current knowledge (and uncertainties) of the causes and consequences of the range of reproductive systems seen in nature. This issue stems from a Jacques Monod conference and we are extremely grateful to Tanja Schwander, Gabriel Marais and Denis Roze for guest editing this issue, plus all the authors and reviewers. JEB would welcome future offers of special issues, which should be addressed to the editorial office at jebeditorial@eseb.org